Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
Ocean Sci., 12, 137-151, 2016
https://doi.org/10.5194/os-12-137-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
18 Jan 2016
Temporal evolution of the momentum balance terms and frictional adjustment observed over the inner shelf during a storm
M. Grifoll1,2, A. L. Aretxabaleta3, J. L. Pelegrí4, and M. Espino1,2 1Technical University of Catalonia, Barcelona, Spain
2International Centre of Coastal Resources Research, Barcelona, Spain
3US Geological Survey, Woods Hole, MA, USA
4Departament d'Oceanografia Física i Tecnològica, Institut de Ciències del Mar, CSIC, Barcelona, Spain
Abstract. We investigate the rapidly changing equilibrium between the momentum sources and sinks during the passage of a single two-peak storm over the Catalan inner shelf (NW Mediterranean Sea). Velocity measurements at 24 m water depth are taken as representative of the inner shelf, and the cross-shelf variability is explored with measurements at 50 m water depth. During both wind pulses, the flow accelerated at 24 m until shortly after the wind maxima, when the bottom stress was able to compensate for the wind stress. Concurrently, the sea level also responded, with the pressure-gradient force opposing the wind stress. Before, during and after the second wind pulse, there were velocity fluctuations with both super- and sub-inertial periods likely associated with transient coastal waves. Throughout the storm, the Coriolis force and wave radiation stresses were relatively unimportant in the along-shelf momentum balance. The frictional adjustment timescale was around 10 h, consistent with the e-folding time obtained from bottom drag parameterizations. The momentum evolution at 50 m showed a larger influence of the Coriolis force at the expense of a decreased frictional relevance, typical in the transition from the inner to the mid-shelf.

Citation: Grifoll, M., Aretxabaleta, A. L., Pelegrí, J. L., and Espino, M.: Temporal evolution of the momentum balance terms and frictional adjustment observed over the inner shelf during a storm, Ocean Sci., 12, 137-151, https://doi.org/10.5194/os-12-137-2016, 2016.
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Short summary
We investigate the rapidly changing equilibrium between the momentum sources and sinks during the passage of a single two-peak storm over the Catalan inner shelf (NW Mediterranean Sea). At 24m water depth, a primary momentum balance between acceleration, pressure gradient and frictional forces (surface and bottom) is established. The frictional adjustment timescale was around 10h, consistent with the e-folding time obtained from bottom drag parameterizations.
We investigate the rapidly changing equilibrium between the momentum sources and sinks during...
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